The term “cover crop” is one of those bits of farming lingo at least mildly familiar to even the Agriculturally Uninitiated - even though they might not know exactly what it means.This is probably because cover crops are so valuable, protecting otherwise bare soil against erosion.
A related term, perhaps less familiar to the general public, is “green manure.” A vivid phrase which might conjure up something unpleasant you found in your kid’s diaper, it actually means plant matter which has been added to the soil to improve its fertility.
Because cover crops are inevitably added to the soil, they also become green manure, so these terms are fairly interchangeable. Cover crops aren’t usually grown for economic gain, but for the benefits they provide to the production of future crops and the overall soil tilth (physical condition of the soil as it relates to planting and growing).
The plant canopy of cover crops reduces the impact of raindrops on the soil surface, slowing the breakdown of soil aggregates - groups of soil particles that bind to each other more strongly than they bind to adjacent particles. This minimizes soil erosion and runoff and increases water infiltration.
Decreased soil loss and runoff also slows the loss of valuable nutrients, pesticides, herbicides, and possible pathogens associated with manure that can negatively impact our watersheds and pose a human health risk.
Cover crops aren’t usually grown for economic gain, but for the benefits they provide to the production of future crops and the overall soil tilth.
Cover crops are an amazing source of organic matter which can improve soil structure and help absorb and conserve soil moisture. Over time, cover crops will increase soil’s stability and its capacity to hold water and nutrients for future crops. Organic matter is also a great source of carbon and nitrogen, which will benefit soil microbiology and overall plant health.
Cover crops are a great source of quality feed for grazing livestock or hay. They provide habitat for wildlife, beneficial insects, and pollinators. They suppress soil disease and pests and thus protect the overall plant health of the crop.
They can also serve as bioremediators, taking up any excess nutrients and protecting our water resources. Fast growing covers will usually outcompete weeds by stealing light, water, and nutrients.
At a time when we’re facing immense climate uncertainty, our goal as stewards of the land is to protect and nurture our soils.
Legume cover crops (clover, alfalfa, vetch) add nitrogen back into the farming system - although they are slow to establish and compete rather poorly with faster growing weeds. This addition of nitrogen can reduce the ongoing application of purchased fertilizers, lower costs of crop production, and mitigate nitrogen losses to the environment.
A good cover crop will also trap and store underutilized fertilizer, nutrients from manure, or mineralized organic nitrogen. This allows future crops to use them while reducing runoff and leaching.
The benefits of using cover crops are pretty wide ranging, and at a time when we’re facing immense climate uncertainty, our goal as stewards of the land is to protect and nurture our soils.
We have an obligation to do all we can at this crucial climate juncture and if we can protect our soils, we’ll be more capable of producing clean healthy food and botanical medicines that boost our own health and that of everyone we serve.